1. Field
The present invention relates to electrical storage systems, such as batteries.
Embodiments of the present invention illustrated herein relate to prediction as well as to tracking of performance of an electrical energy storage system.
2. Description of the Related Art
The usefulness of electrical energy storage systems (ESS), for example, comprising one or more batteries may depend on certain specified properties, referred to as key performance indicators (KPI). An example of a KPI for an ESS is its energy capacity, simply referred to as “capacity” in this text. A KPI such as capacity typically varies significantly during the lifetime of the ESS, and the variation may depend on several factors.
Therefore, a supplier of an ESS often cannot guarantee a single value that a KPI would retain over its whole lifecycle. A customer or consumer, on the other hand, needs a certain expectation of how the performance of his ESS will evolve over the lifecycle to assess the value of this asset. Consequently, there may be a need for a method that enables a supplier to guarantee a customer exactly how a KPI of an ESS will evolve over its lifetime.
Due to the complex temporal evolution of the KPIs and current ESS products typically being relatively young and not mass tested, suppliers often do not provide any KPI guarantees at all. Alternately, some of the approaches that have been used by ESS suppliers include, for example:                KPI guarantees if very strict usage regimes are followed, or        Guarantees describing evolution of a KPI as a relatively simple function of lifetime.        
The state of the art approaches may have the disadvantage that they will usually predict a KPI very conservatively, which can lead to suboptimal investment decision and planning. Sometimes prediction of temporal evolution of the KPI is almost impossible if they depend strongly on usage history.